A shoe-making last is the most important component in the production of footwear. A last is the solid, three-dimensional mold over which footwear is made and the last dictates the size, shape and fit of the footwear made thereon. When manufacturing shoes, and other footwear, the last is firmly mounted, and the pieces of shoe material, whether upper or sole material, are placed around the last and attached together to make the footwear.
The interior space of any item of footwear is an exact reflection of the exterior shape of the last regardless of the outer cosmetic features or styling of the footwear. All footwear built on the same last has the same interior space and dimensions and generally yields the same fit for a particular wearer. Consequently, the shape and configuration of the last is critical in order to make footwear which fits comfortably on the foot, provides adequate support and performs essentially as an extension of the human foot, as is desired.
Footwear manufacturing is a precise and sometimes tedious process. Particularly, the last must be precisely shaped, sized and graded to produce useable footwear. Conventional lasts are not casts of the feet, and indeed, a cast of the foot is not suitable to use as a last. Rather, a conventional last is a precise and highly refined piece of equipment used in footwear production and is precisely measured and referenced according to the dictates of conventional last technology. The last of the present invention is also a precise and refined piece of equipment but is drastically different from conventional lasts, and a brief analysis of the various precise measurements and dimensions associated with conventional lasts is helpful in illustrating the differences between last of the invention and conventional footwear lasts.
FIGS. 5, 5A, 5B and 6 illustrate conventional footwear lasts, and particularly, the figures show a conventional last 5 for a woman's high-heel shoe. While a man's shoe last would generally have a lower heel, the overall shape and dimensions of the last illustrated and discussed herein are generally common to all conventional lasts. FIGS. 5, 5A and 5B and 6 clearly illustrate a critical and common feature of all conventional lasts, i.e. a flat bottom surface 10 and a distinct and sharply-angled last bottom featherline 12, defined by the sharp angle created when the upper surface 14 of the last meets the flat sole surface 10. Base plane 18 is a plane to which the last is referenced in its proper or upright attitude for the purpose of defining the precise last terms and dimensions. The conventional last has a front cone 20 and a back cone 22. While the sole surface 10 is generally flat, there may be a very slight transverse and downward curvature illustrated in FIG. 5B and defined as the crown 24. At the rear of the last, point 25 is defined as the heel point and is the rearmost point of the heel seat 29 on the featherline 12. Reference line 26 defines the back cone height. Point 28 is the breast line point which defines the forward boundary of the heel seat 29. The heel seat 29 is defined as the bottom surface of the heel end of the last 5. The heel elevation of the last is indicated by numeral 30 while the wedge angle 32 of the heel seat 29 defines the angle between the base plane 18 and the heel seat 29. Referring to FIG. 5A, the back part width 36 is the width of the heel seat 29 measured parallel to the heel seat featherline plane at a specified distance forward of the heel point 25 and above the heel seat 29, while the heel seat width 38 is the greatest width of the heel seat 29 measured from the sharp featherline on one side of the heel seat 29 to the other featherline generally perpendicular to a defined heel center line 37.
Referring to FIG. 6, the stick length 40 designates the overall length of the last 5. In the front cone 20 of last 5, a vamp point 42 is defined on the top of the forepart 44 of the last 5. In the back part 46 of the last and forward of the heel seat 29 is the shank 47. At the point of intersection of the shank 47 and the forepart 44 of the last, a last joint breakpoint 48 is defined. The last joint breakpoint 48 lies in a plane which passes through the heel point 25 and is perpendicular to the plane of the last centerline 37. The circumferential measurement across forepart 44 of the last 5, between the vamp point 42 and the last joint breakpoint 48, is designated as the joint girth 50. Another circumferential measurement, the instep girth 51, is measured around the last front cone 20 and passes through a defined instep point 52. The waist girth 54 is the circumferential dimension around the last 5 between the joint girth 50 and the instep girth 51.
The throat opening 56 of the last is defined as the distance in a straight line from the vamp point 42 to a back seam tack point 58 which is defined on the last above the heel seat 29. While the long heel girth 60 is defined as the dimension between the heel point 25 and the instep point 52.
The forepart 44 of conventional lasts also are similarly shaped and are defined by precise dimensions referenced from the base plane 18 and particularly from the sharply-angled featherline 12 at the toe region of the last. As illustrated in FIG. 5B, the sharply-angled featherline 12 in the forepart 44 is defined by the flat sole surface 10 of last 5 meeting a wall portion 62 around the periphery of the last forepart 44. The wall portion 62 is characterized by relatively vertical sides. The perimeter defining the intersection between the vertical walls 62 and the upper surface of the forepart 44 of the last 5 is designated as the ridge 64 of the last. A toe point 66 is defined as the forwardmost point of the toe end 67 of the last along the featherline 12. Conventional lasts sharply recede from a point of full toe thickness to the toe point 66. In the toe end 67, the sharp slope or recession of the upper surface of the last down to the angled featherline 12 at the toe point 66 is termed the toe recede. Conventional lasts also utilize an elevated toe and as illustrated in FIG. 5, the flat sole surface 10 in the toe end 67 angles upwardly from the base plane to the toe point 66. The vertical distance between the base plane 18 and the toe point 66 of the last is defined as the toe spring 69. The toe spring 69 is measured for a last having a particular heel elevation 30.
Because of the generally planar sole surface 10, each last 5 has a single tread point or tread area 68 where contact is made with the base plane 18 when the last 5 is in its upright or primary position. Referring again to FIG. 5, if the last 5 was allowed to rest on the base plane, there would generally only be two points or surface areas of contact between the last 5 and the base plane--the tread point or area 60 defined as the desired contact point or area forward of the last joint breakpoint 48, and a point or area proximate the heel seat 29.
The above-discussed dimensions and defined reference points are not all of the precise last dimensions or points of measurement which are utilized in the manufacturing of shoes with conventional lasts. From the measurement points and dimensions discussed hereinabove, it becomes evident that conventional last technology and the traditional manufacturing of footwear is more than simple molds and assembling various material pieces together to form footwear which fits comfortably around the human foot. As is illustrated, the fundamental definition of a conventional last and the defined reference points and dimensions are all heavily reliant upon a flat sole surface and the sharply-angled featherline surrounding the last. Indeed, all current shoe manufacturing utilizes conventional lasts and last technology with the only difference between different shoes being variations in some of the length, height and girth dimensions and measurements defined by conventional last technology. Conventional lasts and last technology generally does not provide footwear which works in harmony with the human foot.
By way of background, conventional footwear manufacturing is essentially the process of joining two basic parts, the upper and the bottom, together around the last. The conventional footwear upper includes a vamp which covers the toe region and forepart of the last, and the quarters, which cover the sides and back part of the last. The bottom of conventional footwear consists primarily of an insole, a sole and a heel. The top of the footwear which surrounds the opening for the foot is called the top line 87. The lower extremity where the upper meets the sole is called the feather edge. Referring to FIG. 6A, numeral 71 designates the angled feather edge of a conventional women's shoe 73. In a shoe 73 made on a conventional last as shown in FIGS. 5, 5A, 5B and 6, the sharply angled feather edge 71 clearly delineates the footwear upper 75 from the flattened footwear sole 77. FIG. 6B illustrates a conventional man's shoe 79 built on a traditional last similar to the last in FIGS. 5, 5A, 5B and 6 except with a different heel elevation, toe shape and joint girth among some other differences. The man's shoe 79 also illustrates a respective sharply-angled feather edge 81 created by the angled featherline 12 of the last 5. When upper patterns are cut for conventional footwear, an additional margin of material is added to the feather edge which allows the upper to be wrapped around the sharp featherline and attached to the rest of the footwear. The additional material that is necessary is termed the "lasting allowance," because it is dictated by the shape of a conventional last. Furthermore, conventional shoes often must include a mass of material 83 termed the arch support for artificially supporting the foot due to the positioning of the foot on a rigid sole 85.
The term "making" refers to the process of bringing together the components of the upper and bottom and joining them to "make" footwear. There are numerous ways in which footwear can be made and each method of construction shares essentially a sequence of three steps which result in the components being brought together around a conventional last and assembled into footwear. The three basic steps to footwear construction are: (1) assembly; (2) lasting; and (3) attaching.
Assembly refers to the bringing together of all the components of the shoe including stitched and closed uppers and the insoles, soles and heels of the bottom. Some footwear may have additional components depending upon the method of construction, type of footwear and the intended application. However, the components which are assembled together are, in some form or another, common to all footwear which are intended for normal wear as distinguished from slippers or water protectant overshoes and some other specialty footwear items.
When all the necessary components have been assembled, components are matched with each other and then married to a last which matches the style, size and width of the assembled components. All the matched and married components and their corresponding lasts are identified in groups prior to proceeding in the manufacturing process.
Following completion of the assembly, lasting takes place. Lasting refers to a process of stretching the upper material over the conventional manufacturing last and pulling the lasting allowance around the last bottom featherline. The lasting allowance is then secured to the flat sole surface 10 of the last either with tacks or with adhesive. The flat insole must then match the flat sole surface of the last. When lasted correctly, the upper material conforms itself to the contours of the last and retains the contours even when the last is ultimately removed. Upon completion of lasting, the featherline of the last, translated into the sharply-angled feather edge around the insole, clearly defines the upper from the bottom of the footwear just as the last bottom featherline clearly defines the upper surface of the last from the flattened sole surface of the last.
Upon completion of the lasting steps, the footwear is ready for attachment of the sole. "Attaching" refers to the process of affixing a flat sole to the lasted upper material using adhesives, nails, pegs or some combination of them. There are various types of attachment methods including direct attachment where the sole is attached to the bottom of the insole to which the upper has been attached, and indirect attachment wherein a layer or layers of material are placed between the insole and the outer sole and the outer sole is attached thereto. The styles and materials of the shoe, along with the construction and available equipment dictate the attaching process utilized.
Regardless of the method of construction and attachment of the material components used to make conventional footwear, the methods of footwear manufacturing utilize and require a conventional last which has a shape fundamentally different than that of the human foot for which the footwear product is designed. The machinery and equipment used for lasting of the upper and attachment of the outer sole to the lasted upper along with the finishing operations requires that the last have a last bottom featherline and a flat sole surface for proper sole attachment.
All existing shoe lasts, whether for mass manufacturing or custom footwear exhibit a flat sole surface which meets the upper last surface at approximately a 90.degree. angle defined by the last bottom featherline. The last bottom featherline dictates a sharply-angled feather edge in the finished footwear. Industry reference publications, such as Manual of Shoe Making, C. & J. Clark, Ltd. Copyright 1976; American Last Making, Carl Adrian, Copyright 1991; Professional Shoe Fitting, National Shoe Retailers Association, Copyright 1984;and Last Terms and Terminology, American Footwear Industry, Copyright 1976, all emphasize the importance and need for a last having a sharply-angled bottom featherline to make it possible to accurately attach the outer soles and subsequently finish the footwear. Furthermore, the patents of MacDonald U.S. Pat. No. 2,002,580 and Keder U.S. Pat. No. 3,262,142 illustrate in the figures and discuss in the text the difference between a foot cast and a resulting last for manufacturing footwear.
In short, conventional footwear lasts are not molds of the human foot. While a cast of a foot might be utilized for measurement purposes to make a custom pair of shoes, a foot cast cannot function as a last. A last, by conventional teaching, must have a flat sole surface, an elevated heel and sharp angling between the upper surface of the last and the sole surface to create a sharply-angled bottom featherline. Furthermore, the heel surface must be squared to a base plane and the last shaped such that a line drawn vertically down the middle of the back of the last is generally perpendicular to the ground or base plane. Despite conventional last technology and the footwear manufactured therewith, such conventional lasts have fallen short of the goal of providing footwear which works in harmony with the human foot. Such disharmony is created by the differences between a human foot and a conventional last.
For example, conventional lasts have sharply defined featherlines at the point of transition from the flat sole surface or crown to the vertical sidewalls of the last between the defined featherline and the last ridge. The human foot is not sharply angled. The last ridge and sharply-angled contours of a conventional last only take into account generally the static shape of the foot whereas during the wearing of footwear, the foot will undergo dynamic shape changes as well. Conventional lasts utilize heel curves which are overly exaggerated to promote a gripping of the foot by the footwear. The heel seat of a conventional last is angled to correspond with introduction of an elevated heel onto the sole surface. The heel of a human foot is not elevated and has no such heel pitch. In the toe region of a conventional last, the toe profile decreases or recedes to the sharply defined featherline in the forepart of the last while human toes generally maintain a uniform thickness throughout their length. Furthermore, an upward toe spring of the last forepart is utilized while the human foot has no such toe spring.
As discussed above, the heel seats of conventional lasts are generally unnaturally raised to different heel elevations to accommodate the heel for the footwear being manufactured. The only accommodation for the natural and dynamic shape of the human foot in the conventional last might be the fitting of the width of the last and the modest sloping to accommodate a sloped, flat shank between the elevated heel seat and the forepart of the last. While the slope between the forepart and heel seat provides a slight transition in the conventional last, the shank area still has a sharply-angled featherline and the sole surface at the shank is generally planar in a transverse direction to match with the flat sole surface and sharply-angled featherline existing in other areas on the rest of the last.
Still further, the conventional last is engineered to distribute the pressure of standing, walking, running or jumping across 100% of the bottom surface of the last, i.e., across 100% of the rigid and flat sole surface. However, the average human foot is engineered to distribute such pressures across approximately 75-80% of the bottom surface of the foot. Therefore, conventional last technology dictates that the footwear manufactured thereon will unnaturally affect the weight bearing and propulsion characteristics of the foot.
Another characteristic of a conventional last which deviates from a natural foot shape is the orientation of the flat sole surface perpendicular to a last centerline plane which is defined by the last centerline 37 as shown in FIG. 6. The heel seats of all conventional lasts are squared to be perpendicular to the centerline plane. However, the intersection of a plane defined by the back of the human lower leg and a horizontal ground or base plane on which the human foot rests is not perpendicular. Thus footwear manufactured from conventional lasts contains and binds the foot in the heel region and in an unnatural position.
As a result of the shape and dimensions of conventional lasts, the lasts and the footwear manufactured thereon have fallen short of the goal of providing footwear which works in harmony with the human foot and thus do not provide comfort to the wearer during standing, walking or running. One major drawback with conventional last is the flat bottom sole surface which dictates that a flat, rigid piece of sole material be attached to footwear upper material at the sharply-angled last featherline, thus producing footwear which has an approximately 90.degree. angled feather edge. The foot is thereby supported artificially on a stiff, flat platform. The human foot at rest and particularly in motion has a tendency to want to fall off the end of the stiff sole platform of the shoe, thus increasing the risk of ankle injuries. The drawbacks of the sharply-angled feather edge of a shoe made from a conventional last are exacerbated by the elevation of the heel seat, the recession of the toe, the unnatural forward pitch of the heel seat and the unnatural upper spring of the toe region of the last.
To offset some of the effects of the stiff platform on the human foot, shoe manufacturers must artificially reinforce the underside of the wearer's foot by placing a mass of material on the inside of the shoe to coincide with and bolster the foot's natural arches. For example, FIG. 6B illustrates the arch support 83 underneath the foot but above the feather edge 81 of men's footwear 79 from a conventional last. However, as can be appreciated, the natural human foot neither has nor requires what is commonly referred to as "arch support." The unnatural stiff support 83 and arch reinforcement in shoes made using conventional lasts therefore further results in a disharmony between the foot and the shoe which can produce, among other things, foot discomfort, back pain and an increased risk of injury.
The motivation behind the shape and dimensions of a conventional last is to achieve more efficient and economical manufacturing of footwear because, essentially, a last is a piece of mechanical equipment for making footwear. However, it is well known by knowledgeable medical and footwear person that conventional lasts yield footwear that eventually damages the feet of some if not most of the wearers, and also diminishes the physical capabilities of the wearers by interfering with the human body's natural operations. While more comfortable and biomechanically correct footwear is desired, to date, it has not been possible to efficiently and economically produce footwear without utilizing conventional lasts and last technology and thus creating footwear having the drawbacks associated therewith and discussed hereinabove.
The shortcomings of footwear manufactured on conventional lasts is evidenced by the fact that approximately 73% of persons in the United States experience some form of problems with their feet. Such problems take many forms including corns, callouses, bunions, blisters, ingrown nails, hammer toes and other deformities and maladies of the foot. However, only 3% of persons in non-shoe wearing countries experience any sort of foot problems, and those persons skilled in the art in both footwear and medicine agree that footwear designed with conventional lasts is the culprit of such statistical variations.
Accordingly, there is a very definite need for a footwear manufacturing last which addresses the shortcomings of conventional lasts and provides footwear which will reduce if not eliminate many of the foot problems associated with footwear manufactured on conventional lasts.
It is further an objective of the invention to provide a piece of equipment for mass-manufacturing footwear which is more in harmony with the human foot, both at rest and in motion.
It is still further an objective of the present invention to create footwear which is biomechanically more in harmony with the shape of the human foot to reduce and eliminate the shortcomings of footwear produced with a conventional last.
It is another objective to present a last which may be readily sized and graded to produce footwear for a large variety of wearers.
It is still another objective of the present invention to provide footwear manufactured with the last of the present invention which incorporates the unique design of the invention last and provides comfort, stability, and proper weight distribution to a wearer.